small server problem

I have a problem with this small server im writing. It accepts one person, but when it accpets another person, nothing happends. Its a chat client. The first person to login gets in and is able to type text. The next person isint able to do anything. This could be a problem with the threading but im not sure. can anyone help me out?

here is the code, I think it has something to do with the threading.
import java.io.*;
import java.net.*;
public class SimpleThreadedServer3
{
static final int portNumber = 5095;
private ServerSocket ss;
private InetAddress addr;
private PrintWriter writer;
private String messageIn,messageOut;
private BufferedReader reader;
public static void main(String [] args)
{
new SimpleThreadedServer3().initiateStartUp();
}
public void initiateStartUp()
{
try{
addr = InetAddress.getLocalHost();

System.out.println("Creating Server Socket at:"+portNumber+" . . . ");
System.out.println("At Host:"+ addr.getHostName()+" . . .");
System.out.println("At Address:"+ addr.getHostAddress()+" . . .");
ss = new ServerSocket(portNumber);

System.out.println("System Online ...");
while(true)
{
Socket sock = ss.accept();
writer = new PrintWriter(sock.getOutputStream());
System.out.println(sock+ "I am a white man");
String m = "stinky";
writer.println(m);

new Thread(new ClientHandler(sock)).start();
}

}catch(IOException e)
{
System.out.println(e);
}
}
class ClientHandler implements Runnable
{
private Socket sock;
public ClientHandler(Socket s)
{
try{
sock = s;

reader = new BufferedReader(new InputStreamReader(sock.getInputStream()));
System.out.println(reader+"stinky bear");
String messageIn;
while((messageIn = reader.readLine())!=null)
{
System.out.println(messageIn);
writer.println(messageIn);
}
}catch(Exception e)
{
System.out.println(e);
}
}
public void run()
{
String messageOut;
try{
while((messageOut = reader.readLine())!= null)
{
System.out.println(messageOut);
sendToAll(messageOut);
}
}catch(Exception e)
{
System.out.println(e);
}
}
}
public void sendToAll(String messageOut)
{
try{
writer.println(messageIn);
writer.println(messageOut);
writer.flush();
}catch(Exception e)
{
System.out.println(e);
}
}
}

can anyone help me out?

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